Musée du Panthéon National Haïtien (MUPANAH) is a state-run museum focusing on heroes of the Haitian revolution, Haitian history in general, and Haitian culture. You can take a tour (in English, Spanish, or French) to learn about history from the Taínos to the present day.
Some of the most interesting things to see including the bell used to announce independence, the gun with which Henri Christophe committed suicide, a bunch of torture instruments, and the anchor of Christopher Columbus's ship, the Santa Maria.
If you get a bad guide (fairly common!) just complain to management. The guided tour is included in the cost of admission. Tipping is VERY optional.